Future 5G communications links are expected to support data rates 50 times faster than current 4G LTE networks. The enabling infrastructure includes radio frequency (RF) front-ends that can handle this data increase using transceivers that are wideband, but also very small in size and weight and low in power (low SWaP). As such, there is a growing interest in reducing the size of ultra-wideband (UWB) apertures and RF electronics to enable compact integration on small platforms. However, the current spectrum suffers from congestion and limitations on available bandwidth, so there is a need for advanced techniques to enhance the efficient access to this spectrum, such as full duplex systems or higher order modulation and coding schemes. Such techniques are often associated with hardware and computational complexities. The latter might be avoided by exploring the yet unused millimeter-wave (mm-wave) spectrum, which offers more bandwidth and much higher data rates.
Concurrently, the small size of RF devices and antenna apertures at mm-waves provides an impetus for realizing low profile and portable systems. Nevertheless, mm-wave technologies suffer from high path-loss and atmospheric absorption that drastically reduce the communication range. To compensate for the path loss, high gain beamforming antenna array systems are required, but traditional analog and digital beamformers are narrowband, power-hungry, and SWaP-inefficient.